Electronic die singulation method

ABSTRACT

In one embodiment, die are singulated from a wafer having a back layer by placing the wafer onto a carrier substrate with the back layer adjacent the carrier substrate, forming singulation lines through the wafer to expose the back layer within the singulation lines, and applying a pressure substantially uniformly along the second major surface to batch separate the layer of material in the singulation lines. In one embodiment, a fluid filled vessel can be used to apply the pressure.

CROSS-REFERENCE TO RELATED APPLICATION

Not applicable.

BACKGROUND

The present invention relates, in general, to electronics and, moreparticularly, to methods for forming electronic devices such assemiconductor dies.

In the past, the semiconductor industry utilized various methods andequipment to singulate individual semiconductor die from a semiconductorwafer on which the die was manufactured. Typically, a technique calledscribing or dicing was used to either partially or fully cut through thewafer with a diamond cutting wheel along scribe grids or singulationlines that were formed on the wafer between the individual die. To allowfor the alignment and the width of the dicing wheel each scribe gridusually had a large width, generally about one hundred fifty (150)microns, which consumed a large portion of the semiconductor wafer.Additionally, the time required to scribe each singulation line on thesemiconductor wafer could take over one hour or more. This time reducedthe throughput and manufacturing capacity of a production facility.

Other methods, which have included thermal laser separation (TLS), laserablation dicing, and plasma dicing, have been explored as alternativesto scribing. Plasma dicing is a promising process compared to scribingand other alternative processes because it supports narrower scribelines, has increased throughput, and can singulate die in varied andflexible patterns. However, plasma dicing has had manufacturingimplementation challenges. Such challenges have includednon-compatibility with wafer backside layers, such as back metal layers,because the etch process has been unable to effectively remove orseparate the backside layers from the singulation lines. Removing orseparating the backside layers from the scribe lines is necessary tofacilitate subsequent processing, such as pick-and-place and assemblyprocesses.

Accordingly, it is desirable to have a method of singulating die from asemiconductor wafer that removes or separates the backside layers fromwithin the singulation lines. It would be beneficial for the method tobe cost effective and to minimize any damage to or contamination of theseparated die.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a reduced plan view of an embodiment of a wafer inaccordance with the present invention;

FIG. 2 illustrates a cross-sectional view of the wafer of FIG. 1 mountedto a carrier substrate in accordance with an embodiment of the presentinvention;

FIG. 3 illustrates a top view of the embodiment of FIG. 2;

FIGS. 4-5 illustrate partial cross-sectional views of the wafer of FIG.1 at various stages in a process of singulating die from the wafer inaccordance with an embodiment of the present invention;

FIG. 6 illustrates a cross-sectional view of the wafer of FIG. 1 at asubsequent stage of singulation in accordance with an embodiment of thepresent invention;

FIG. 7 illustrates an enlarged partial cross-sectional view of theembodiment of FIG. 6 in accordance with reference portion 7-7;

FIG. 8 illustrates the wafer of FIG. 1 after singulation and at afurther stage of manufacture in accordance with an embodiment of thepresent invention; and

FIG. 9 illustrates a flow chart of a batch singulation method inaccordance with an embodiment of the present invention.

For simplicity and clarity of the illustration, elements in the figuresare not necessarily drawn to scale, and the same reference numbers indifferent figures denote the same elements. Additionally, descriptionsand details of well-known steps and elements are omitted for simplicityof the description. For clarity of the drawings, certain regions ofdevice structures, such as doped regions or dielectric regions, may beillustrated as having generally straight line edges and precise angularcorners. However, those skilled in the art understand that, due to thediffusion and activation of dopants or formation of layers, the edges ofsuch regions generally may not be straight lines and that the cornersmay not be precise angles. The terms first, second, third and the likein the claims or/and in the Detailed Description of the Drawings, asused in a portion of a name of an element are used for distinguishingbetween similar elements and not necessarily for describing a sequence,either temporally, spatially, in ranking or in any other manner. It isto be understood that the terms so used are interchangeable underappropriate circumstances and that the embodiments described herein arecapable of operation in other sequences than described or illustratedherein. Furthermore, the term “major surface” when used in conjunctionwith a semiconductor region, wafer, or substrate means the surface ofthe semiconductor region, wafer, or substrate that forms an interfacewith another material, such as a dielectric, an insulator, a conductor,or a polycrystalline semiconductor. The major surface can have atopography that changes in the x, y and z directions. Also, it is to beunderstood that where it is stated herein that one layer or region isformed on or disposed on a second layer or another region, the firstlayer may be formed or disposed directly on the second layer or theremay be intervening layers between the first layer and the second layer.In addition, as used herein, the term formed on is used with the samemeaning as located on or disposed on and is not meant to be limitingregarding any particular fabrication process.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a reduced plan view that graphically illustrates a wafer 10 ata later step in fabrication. In one embodiment, wafer 10 can be asemiconductor substrate. Wafer 10 includes a plurality of semiconductordie, such as die 12, 14, 16, and 18, that are formed on or as part ofsemiconductor wafer 10. Die 12, 14, 16, and 18 are spaced apart fromeach other on wafer 10 by spaces in which singulation lines are to beformed or defined, such as scribe lines or singulation lines 13, 15, 17,and 19. As is well known in the art, all of the semiconductor die onwafer 10 generally are separated from each other on all sides by areasor spaces where scribe lines or singulation lines, such as singulationlines 13, 15, 17, and 19 are to be formed. Die 12, 14, 16, and 18 can beany kind of electronic device including semiconductor devices such as,diodes, transistors, discrete devices, integrated circuits, sensordevices, optical devices, or other devices known to one of ordinaryskill in the art. In one embodiment, wafer 10 has completed waferprocessing including the formation of a backside layer described later.

FIG. 2 illustrates an enlarged cross-sectional view of wafer 10 at anearly step in a die singulation method in accordance with an embodiment.In one embodiment, wafer 10 is attached to a carrier substrate, transfertape, or carrier tape 30 that facilitates supporting the plurality ofdie on wafer 10 after the die are singulated. Such carrier tapes arewell known to those of skill in the art. In one embodiment, carrier tape30 can be attached to a frame 40, which can include frame portions orportions 401 and 402. In one embodiment, frame 40 is made of a rigidmaterial, such as stainless steel. As illustrated, carrier tape 30 canbe attached to surface 4010 of frame portion 401 and to surface 4020 offrame portion 402 using, for example, the adhesive side of carrier tape30.

In the cross-section illustrated, wafer 10 can include a bulk substrate11, such as a silicon substrate, which can include opposing majorsurfaces 21 and 22. In other embodiments, bulk substrate 11 can compriseother semiconductor materials such as heterojunction semiconductormaterials or substrate 11 can be an insulating material such as ceramicmaterials. In one embodiment, contact pads 24 can be formed along, in,on, or above portions of major surface 21 to provide for electricalcontact between structures formed within substrate 11 and next levels ofassembly or external elements. For example, contact pads 24 can beformed to receive bonding wires or clips that subsequently may beattached to contact pads 24, or contact pads 24 can be formed to receivea solder ball, bump or other type of attachment structure. Contact pads24 generally can be a metal or other conductive material. Typically, adielectric material 26 such as, a blanket deposited dielectric layer canbe formed on or overlying major surface 21 to function as a passivationlayer for wafer 10. In one embodiment, dielectric material 26 can be amaterial that etches at a slower rate than that of substrate 11. In oneembodiment, dielectric material 26 can be a silicon oxide, siliconnitride, or polyimide when substrate 11 is silicon. It should also benoted that a separate polymer protective layer, such as a patternedprotective layer, can be used to protect the areas not intended to beetched during subsequent processing. In one embodiment, the patternedprotective layer can be a patterned photoresist layer. An example ofsuch a protective layer is noted as element 35 in FIG. 4 describedlater.

In one embodiment, openings can be formed in dielectric material 26 (andother dielectric layers that can be formed above or below dielectricmaterial 26) to expose underlying surfaces of contact pads 24 andsurfaces of substrate 11 where singulation lines 13, 15, 17, and 19 areto be formed. In one embodiment, the patterned photoresist layerdescribes previously can be used to form the openings with an etchprocess. As illustrated in FIG. 2 and in accordance with the presentembodiment, wafer 10 further includes a layer of material 28 formed onor overlying major surface 22 of wafer 10. In one embodiment, layer 28can be a conductive back metal layer. Layer 28 can be any suitableconductive material appropriate for electronic technology. In oneembodiment, layer 28 can be a multi-layer metal system such as,titanium/nickel/silver, titanium/nickel/silver/tungsten,chrome/nickel/gold, copper, copper alloys, gold, or other materialsknown to those skilled in the art. In some embodiments, layer 28 isgreater than about one micron in thickness. In other embodiments, layer28 is greater than about two microns in thickness. In still otherembodiments, layer 28 is greater than about three microns in thickness.In another embodiment, layer 28 can be a wafer backside coating (WBC)film, such as a die-attach coating or film. In one embodiment, layer 28can be formed having or provided with recesses, gaps, spaces, orchannels between at least some adjacent die. In a further embodiment,the gaps are substantially aligned with corresponding spaces on theopposite side of wafer 10 where singulation lines 13, 15, 17, 19 will beformed. In another embodiment, layer 28 is separated from the edges ofleast some of the die.

FIG. 3 illustrates a top view of wafer 10 in accordance with thecross-sectional view of FIG. 2 after wafer 10 is be mounted on carriertape 30 with layer 28 against carrier tape 30. In one embodiment,carrier tape 30 is mounted to frame 40. As illustrated in FIG. 3, frame40 can be configured with alignment portions or notches to better assistplacing frame 40 into processing equipment such as the equipmentdescribed herein.

FIG. 4 illustrates an enlarged cross-sectional view of wafer 10 at asubsequent step during a singulation process in accordance with thepresent embodiment. In FIG. 4, a plasma or dry etch singulation processis illustrated. It is understood that other singulation processes can beused. In one embodiment, wafer 10 mounted on carrier tape or film 30 isthen placed within an etch apparatus 300, such as a plasma etchapparatus. In one embodiment, substrate 11 can be etched through theopenings to form or define singulation lines or openings 13, 15, 17, and19 extending from major surface 21. The etching process can be performedusing a chemistry (generally represented as arrows 31) that selectivelyetches silicon at a much higher rate than that of dielectrics and/ormetals. In one embodiment, wafer 10 can be etched using a processcommonly referred to as the Bosch process. In one embodiment, wafer 10can be etched using the

Bosch process in a deep reactive ion etch system. In one embodiment, thewidth of singulation lines 13, 15, 17, and 19 can be from about fivemicrons to about twenty microns. Such a width is sufficient to ensurethat the openings that form singulation lines 13, 15, 17, and 19 can beformed completely through substrate 11 stopping proximate to or on layer28 because of the etch selectivity as generally illustrated in FIG. 5.In one embodiment, layer 28 can be used as a stop layer for the plasmaetch singulation process. In one embodiment, singulation lines 13, 15,17, and 19 can be formed in about five to about thirty minutes using theBosch process. A suitable etch apparatus is available from Plasma-Thermof St. Petersburg, Fla., U.S.A.

FIG. 6 illustrates a cross-sectional view of a back layer separationapparatus 60 configured to hold wafer 10 including frame 40 and carriertape 30. In one embodiment, separation apparatus 60 can be configured toprocess a single wafer and to provide a back layer separation processwhere layer 28 on wafer 10 is separated substantially at the same time(that is, batch separated) compared to other processes that separateonly a localized portion of layer 28 at a time. In other embodiments,separation apparatus 60 can be configured to process multiple waferseach in a batch configuration.

Apparatus 60 can include a compression chamber 62 sized to accommodatewafer 10 and frame 40 depending upon the sizes of such structures. Inone embodiment, compression chamber 62 is bounded on all sides by aplurality of generally vertical sidewalls 63 that extend generallyupward from a lower chamber wall or surface 67. Sidewalls 63 can beattached to lower chamber wall 67 using any suitable attachment devicescapable of maintaining pressure with compression chamber 62. Compressionchamber 62 further includes an upper chamber wall or surface 68, whichcan include an opening 69 to accommodate a compression or pressure plate71 or to provide an entrance for a non-compressible fluid. Compressionchamber 62 and can be any suitable shape appropriate for processingwafer 10 and frame 40 or other holding structures.

Compression plate 71 is movably associated or attached withincompression chamber 62 and adapted to apply a controlled andsubstantially uniform pressure to wafer 10 through a pressure transfervessel 73 containing a fluid 74. In one embodiment, vessel 73 can be afluid filled bladder that is oriented between wafer 10 and compressionplate 71. In one embodiment, vessel 73 comprises a cross-linked polymermaterial that exhibits high elastic deformation, such as a rubber orother materials as known to those of ordinary skill in the art. In oneembodiment, vessel 73 is a static pressure balloon. In one embodiment,fluid 74 can be water. In one embodiment, fluid 74 can be water that isanaerobic (that is, water having low dissolved oxygen content or thathas been deoxygenated). In some embodiments, fluid 74 can be heatedabove room temperature. In some embodiments, fluid 74 can be heated to atemperature in range from about 35 degrees Celsius to about 65 degreesCelsius. In one embodiment, fluid 74 can be heated to a temperature inrange from about 45 degrees Celsius to about 55 degrees Celsius. Inother embodiments, fluid 74 can be a fluid having a higher viscositythan water. In some embodiments, fluid 74 can be liquid-crystallinematerial. In still other embodiments, vessel 73 can be filled with asolid material, such as synthetic microspheres, carbon nanotubes,graphene, or other solid or solid-like materials that can impart ortransfer pressure from compression plate 71 to carrier tape 30 withoutdamaging wafer 10. In some embodiments, vessel 73 can be filled with agas. In accordance with the present embodiment and illustrated in FIG.6, vessel 73 has a horizontal width proximate to wafer 10 that is largerthan the horizontal width or diameter of wafer 10 to facilitate batch ornear simultaneous singulation or separation of layer 28 in scribe lines13, 15, 17, and 19 of wafer 10. That is, vessel 73 is configured oradapted to apply a pressure substantially uniformly along or across allof layer 28 and wafer 10 to provide batch separation of layer 28 in thescribe lines.

In an optional embodiment, a pressure plate 77 can be detachably placedin between vessel 73 and carrier tape 30 above or in spaced relationshipwith wafer 10 and layer 28. In one embodiment, pressure plate 77 can bea low-alloy, medium-carbon steel or high-carbon steel material with highyield strength, such as spring steel. Such a material allows pressureplate 77 to return to its original shape despite any significantbending. In one embodiment, pressure plate 77 can be a generally flatplate where the major surfaces lie in substantially parallel horizontalplanes. In other embodiments, pressure plate 77 can have a lower surface(that is, the surface adjoining carrier tape 30) configured to firstapply pressure to the outer portions of wafer 10 before or slightlybefore pressure applied to the more central portion of wafer 10. Forexample, in one embodiment pressure plate 77 can have a slightly concavemajor surface adjoining carrier tape 30 without pressure applied withvessel 73. In another embodiment, pressure plate 77 can have a slightlyraised ridge, for example, in the shape or form of a ring round an outerperiphery of pressure plate 77.

In some embodiments, a protective film or protective pad 83 is placedbetween wafer 10 and lower chamber wall 67 to protect and/or cushionwafer 10 during the separation of back layer 28. In one embodiment,protective film 83 is a non-adhesive film or a low adhesive film wherethe adhesive strength is selected so as to minimize the occurrence ofindividual die being removed from carrier tape 30 after separation ofback layer 28 has occurred. In other embodiments, protective film 83 canhave a high adhesive strength (that is, higher than the adhesivestrength of carrier tape 30) if it is desired to have the separated dieadhere to protective film 83, for example, for additional processing tothe back side of wafer 10.

In some embodiments, a controlled downward pressure (represented byarrows 701 and 702) is applied through compression plate 71 using, forexample, a stepper motor driving a threaded shaft attached tocompression plate 71. In other embodiments, compression plate 71 can beadjusted using hydraulic or pneumatic techniques. In some embodiments,compression plate 71 can be adjusted manually. It is understood thatapparatus 60 may include other sealing devices, fluid heating anddelivery devices, and measurement and control systems that are notillustrated for the ease of understanding embodiments of the presentinvention. Suitable apparatus that can be configured in accordance withthe description provided herein are available from Instron® of Norwood,Mass., U.S.A. and Geocomp Corporation of St. Johns, N.Y., U.S.A.

FIG. 7 illustrates an enlarged partial cross-sectional view of a portionof apparatus 60 and wafer 10 of FIG. 6 along reference portion 7-7. InFIG. 7, carrier tape 30 is enlarged to show both a singulation filmportion 301 and an adhesive film portion 302 between singulation filmportion 301 and layer 28 on wafer 10. In some embodiments, singulationfilm portion 301 can have a thickness from about 70 microns to about 90microns and adhesive film portion 302 can have thickness from about 20microns to about 40 microns. In accordance with some embodiments,pressure applied from compression plate 71 is transferred and appliedthrough vessel 73 to optional pressure transfer plate 77 to carrier tape30 as generally represented by arrows 701, 702, and 703. The downwardforce applied to carrier tape 30 extrudes adhesive film portion 30 inscribe lines 13, 15, 17, and 19 between die 12, 14, 16, and 18 toseparate away or singulate portions of layer 28 in the scribe lines asgenerally illustrated in FIG. 7. In some embodiments, a downward forcecan be in the range from about 700 KPa to 1400 KPa. In otherembodiments, downward force can be in the range from about 1400 KPa to3500 KPa. One advantage of the present method is that it provides abatch singulation of layer 28 compared to previous processes thatprovide localized singulation of layer 28. The present embodiments thusreduce manufacturing cycle time. Another advantage is that metalseparates cleanly and self-aligned to the die edge and further,remaining material of layer 28 between die will remain on the tape afterthe die are removed with no need to flip the tape to expose and removeor separate the metal.

FIG. 8 illustrates a cross-sectional view of wafer 10 at a further stageof manufacturing. In one embodiment, die 12, 14, 16, and 18 can beremoved from carrier tape 30 as part of a further assembly processusing, for example, a pick-and-place apparatus 81 as generallyillustrated in FIG. 8. As illustrated in FIG. 8 portions 280 separatedfrom layer 28 remain on carrier tape 30. In one embodiment, die 12, 14,16, and 18 can be attached to conductive lead frames or substrates,electrically connected to leads for traces, and encapsulated with aplastic molding compound. In one embodiment, carrier tape 30 can beexposed to a UV light source prior to the pick-and-place step to reducethe adhesiveness of carrier tape 30.

FIG. 9 illustrates a flow chart for batch singulating backside materialin accordance with an embodiment. In step 900, wafer 10 can be placedonto a carrier film, such as carrier tape 30, as generally illustratedin FIG. 2. In accordance with the present embodiment, wafer 10 includesback layer, such as layer of material 28. In some embodiments, layer 28is a conductive metal material. In other embodiments, layer 28 can be aWafer Back Coat (WBC) film, such as a die-attached coating or film. Instep 901, material, such as semiconductor material, is removed fromscribe lines 13, 15, 17, and 19. Semiconductor material can be removedto expose layer 28 in scribe lines 13, 15, 17, and 19, or small amountof material can be left in scribe lines 13, 15, 17, and 19. Statedanother way, a sufficient amount of material is removed so that layer 28can be effectively separated in scribe lines 13, 15, 17, and 19 in asubsequent step. In step 902, wafer 10 on carrier tape 30 is placed inapparatus 60 as described with FIG. 6. In one embodiment, wafer 10 isplaced front side or device side down with layer 28 and carrier tape 30facing upward. In one embodiment, pressure plate 77 can be placedadjacent to carrier tape 30 proximate to wafer 10 and layer 28. A fluidfilled vessel, such as vessel 73, can then placed proximate to pressureplate 77 as generally illustrated in FIGS. 6 and 7. In one embodiment,the fluid filled vessel is filled with deoxygenated water heated totemperature from about 35 degrees Celsius to about 65 degrees Celsius.In step 903, a pressure is applied to the fluid filled vessel using, forexample, a moveable compression plate 71 as described in conjunctionwith FIG. 6. In one embodiment, a pressure range from about 500 KPa to5000 KPa can be used. In one embodiment, the pressure applied to thefluid filled vessel causes portions of the carrier film, for example,adhesive film portion 302, to extrude into the scribe lines, such asscribe lines 13, 15, 17, 19, which batch singulates or simultaneouslyseparates all or major portions of layer 28 from the scribe lines. Inother embodiments, step 903 can applied multiple times (that is, morethan once on the same wafer) with pressure applied, then removed, thenre-applied. In some embodiments, the re-applied pressure can be greaterthan the previously applied pressure. In other embodiments, there-applied pressure can be less than the previously applied pressure. Instill other embodiments, compression plate 71 can be slightly tilted androtated to apply additional pressure around the edge regions of wafer10. In further embodiments, compression plate 71 can be rocked back andforth in multiple directions.

From all of the foregoing, one skilled in the art can determine that,according to one embodiment, a method of singulating a wafer (forexample, element 10) comprises providing a wafer (for example, element10) having a plurality of die (for example, elements 12, 14, 16, 18)formed on the wafer and separated from each other by spaces, wherein thewafer has first and second opposing major surfaces (for example,elements 21, 22), and wherein a layer of material (for example, element28) is formed along the second major surface. The method comprisesplacing the wafer onto a carrier substrate (for example, element 30).The method comprises singulating the wafer through the spaces to formsingulation lines (for example, elements 13, 15, 17, 19), whereinsingulating comprises stopping in proximity to the layer of material.The method comprises applying a pressure substantially uniformly alongthe second major surface to separate the layer of material in thesingulation lines.

In one embodiment of the foregoing method, after applying the pressureportions (for example, element 280) of the separated layer of materialremain on the carrier substrate. In another embodiment, applying thepressure can include applying the pressure through the carrier substratewith a fluid filled vessel (for example, element 73) and the fluidfilled vessel has a width that exceeds that of the wafer. In a furtherembodiment, the fluid filled vessel can contain water. In a stillfurther embodiment, the water can be deoxygenated. In anotherembodiment, the method can further include placing a pressure platebetween the fluid filled vessel and the carrier substrate, and whereinproviding the wafer can comprise providing a semiconductor wafer wherethe layer of material comprises a conductive material, placing the waferonto the carrier substrate can comprise placing onto a carrier tapeattached to a frame, applying the pressure can comprise applying in acompression chamber, and applying the pressure can comprise a pressurefrom about 500 KPa to about 5000 KPa. In a further embodiment, themethod can further comprise heating the wafer while applying thepressure. In a still further embodiment, the wafer can be heated to atemperature from about 35 degrees Celsius to about 65 degrees Celsius.In another embodiment, the method can further comprise placing aprotective film proximate to the first major surface of the wafer beforeapplying the pressure.

From all of the foregoing, one skilled in the art can determine that,according to another embodiment, a method for batch singulating asemiconductor wafer comprises providing the semiconductor wafer (forexample, element 10) having a plurality of die (for example, elements12, 14, 16, 18) formed on the semiconductor wafer and separated fromeach other by spaces, wherein the semiconductor wafer has first andsecond opposing major surfaces (for example, elements 21, 22), andwherein a layer of material (for example, element 28) is formed alongthe second major surface. The method comprises placing the wafer onto acarrier substrate (for example, element 30), wherein the layer ofmaterial is adjacent the carrier substrate. The method comprises etchingthe semiconductor wafer through the spaces to form singulation lines(for example, elements 13, 15, 17, 19) and to expose portions of thelayer of material in the singulation lines. The method comprisesapplying a pressure substantially uniformly along the second majorsurface of the semiconductor wafer through the carrier substrate toseparate the layer of material in the singulation lines.

In one embodiment of the foregoing method, applying the pressure caninclude extruding portions of the carrier substrate into the singulationlines to separate the layer of material, and wherein the portions (forexample, element 280) of the separated layer of material remain on thecarrier substrate. In another embodiment, applying the pressure caninclude using a fluid filled vessel having a width greater than that ofthe semiconductor wafer. In a further embodiment, applying the pressurecan include using a static pressure balloon. In a still furtherembodiment, the static pressure balloon can filled with a heated fluidcomprising one or more of a liquid and a gas. In another embodiment,providing the semiconductor wafer can include providing the layer ofmaterial comprising a conductive material greater than about threemicrons in thickness, and wherein applying the pressure can comprise apressure from about 500 KPa to about 5000 KPa.

From all of the foregoing, one skilled in the art can determine that,according to an additional embodiment, a method of singulating a wafercomprises providing a wafer (for example, element 10) having a pluralityof die (for example, elements 12, 14, 16, 18) formed on the wafer andseparated from each other by spaces, wherein the wafer has first andsecond opposing major surfaces (for example, element s21, 22), andwherein a layer of material (for example, element 38) is formed alongthe second major surface. The method comprises placing the wafer onto acarrier substrate (for example, element 30) having an adhesive portion,wherein the layer of material is adjacent the carrier substrate. Themethod separating the wafer through the spaces to form singulation lines(for example, elements 13, 15, 17, 19), wherein singulating linesterminate in proximity to the layer of material. The method comprisesapplying a pressure across the second surface of the wafer to extrudethe adhesive portion into the singulation lines to separate the layer ofmaterial in the singulation lines, wherein portions (for example,element 280) of the separated layer of material remain on the carriersubstrate.

In one embodiment of the foregoing method the applying step is repeatedmore than once. In another embodiment, applying the pressure cancomprise compressing a static pressure balloon (for example, element 73)having a diameter greater than that of the wafer. In a furtherembodiment, applying the pressure can comprise using a fluid filledvessel (for example, elements 73, 74). In a still further embodiment,the method can futher comprise heating the wafer while applying thepressure. In another embodiment, can further comprise placing a pressureplate (for example, element 77) between the fluid filled vessel and thecarrier substrate before applying the pressure. In a further embodiment,providing the wafer can comprise providing the layer of material havinga thickness greater than about three microns and applying the pressurecan comprise a pressure between about 500 KPa to about 5000 KPa.

From all of the foregoing, one skilled in the art can determine that,according to further embodiment, a method for separating a layer ofmaterial on a wafer comprises providing the wafer (for example, element10) having a plurality of die (for example, element 12, 14, 16, 18)formed on the wafer and separated from each other by singulation lines(for example, elements 13, 15, 17, 19), wherein the wafer has first andsecond opposing major surfaces (for example, elements 21, 22), andwherein a layer of material (for example, element 28) is formed alongthe second major surface, and wherein the singulation lines extend fromthe first major surface and terminate proximate to the layer ofmaterial, and wherein the wafer is attached to a carrier substrate (forexample, element 30). The method comprises simultaneously applying apressure along the entire second major surface of the wafer through thecarrier substrate to separate the layer of material in the singulationlines.

In view of all of the above, it is evident that a novel method isdisclosed. Included, among other features, is placing a substrate havinga layer of material on a major surface of the substrate onto a carriertape, and forming singulation lines through the substrate to exposeportions of the layer of material within the singulation lines. Apressure is substantially uniformly applied along the second majorsurface of the substrate through the carrier tape to separate the layerof material in the singulation lines in a batch configuration. In oneembodiment, the pressure is applied with a fluid filled vessel that iscontrollably compressed against the wafer. The method provides, amongother things, an efficient, reliable, and cost effective process forbatch singulating substrates that include back layers, such as thickerback metal layers or WBC layers.

While the subject matter of the invention is described with specificpreferred embodiments and example embodiments, the foregoing drawingsand descriptions thereof depict only typical embodiments of the subjectmatter, and are not therefore to be considered limiting of its scope. Itis evident that many alternatives and variations will be apparent tothose skilled in the art. For example, other forms of removable supportmaterials can be used instead of carrier tapes.

As the claims hereinafter reflect, inventive aspects may lie in lessthan all features of a single foregoing disclosed embodiment. Thus, thehereinafter expressed claims are hereby expressly incorporated into thisDetailed Description of the Drawings, with each claim standing on itsown as a separate embodiment of the invention. Furthermore, while someembodiments described herein include some but not other featuresincluded in other embodiments, combinations of features of differentembodiments are meant to be within the scope of the invention and meantto form different embodiments as would be understood by those skilled inthe art.

1. A method of singulating a wafer comprising: providing a wafer havinga plurality of die formed on the wafer and separated from each other byspaces, wherein the wafer has first and second opposing major surfaces,and wherein a layer of material is formed along the second majorsurface; placing the wafer onto a carrier substrate; singulating thewafer through the spaces to form singulation lines, wherein singulatingcomprises stopping in proximity to the layer of material; and applying apressure substantially uniformly along the second major surface toseparate the layer of material in the singulation lines.
 2. The methodof claim 1, wherein portions of the separated layer of material remainon the carrier substrate after applying the pressure.
 3. The method ofclaim 1, wherein applying the pressure comprises applying the pressurethrough the carrier substrate with a fluid filled vessel, the fluidfilled vessel having a width that exceeds that of the wafer.
 4. Themethod of claim 3, wherein the fluid filled vessel contains water. 5.The method of claim 4, wherein the water is deoxygenated.
 6. The methodof claim 3 further comprising placing a pressure plate between the fluidfilled vessel and the carrier substrate; and wherein: providing thewafer comprises providing a semiconductor wafer where the layer ofmaterial comprises a conductive material; placing the wafer onto thecarrier substrate comprises placing onto a carrier tape attached to aframe; applying the pressure comprises applying in a compressionchamber; and applying the pressure comprises a pressure from about 500KPa to about 5000 KPa.
 7. The method of claim 1, further comprisingheating the wafer while applying the pressure.
 8. The method of claim 7,wherein the wafer is heated to a temperature from about 35 degreesCelsius to about 65 degrees Celsius.
 9. The method of claim 1 furthercomprising placing a protective film proximate to the first majorsurface of the wafer before applying the pressure.
 10. A method forbatch singulating a semiconductor wafer comprising: providing thesemiconductor wafer having a plurality of die formed on thesemiconductor wafer and separated from each other by spaces, wherein thesemiconductor wafer has first and second opposing major surfaces, andwherein a layer of material is formed along the second major surface;placing the wafer onto a carrier substrate, wherein the layer ofmaterial is adjacent the carrier substrate; etching the semiconductorwafer through the spaces to form singulation lines and to exposeportions of the layer of material in the singulation lines; and applyinga pressure substantially uniformly along the second major surface of thesemiconductor wafer through the carrier substrate to separate the layerof material in the singulation lines.
 11. The method of claim 1 whereinapplying the pressure comprises extruding portions of the carriersubstrate into the singulation lines to separate the layer of material,and wherein the portions of the separated layer of material remain onthe carrier substrate.
 12. The method of claim 1, wherein: placing thewafer comprises placing the wafer onto a carrier tape attached to aframe; singulating comprises plasma etching the wafer; and applying thepressure comprises simultaneously applying the pressure uniformly alongthe entire second major surface.
 13. The method of claim 1, whereinapplying the pressure comprises using a static pressure balloon.
 14. Themethod of claim 13, wherein static pressure balloon is filled with aheated fluid comprising one or more of a liquid and a gas.
 15. Themethod of claim 1, wherein providing the wafer comprises providing thelayer of material comprising a conductive material greater than aboutthree microns in thickness, and wherein applying the pressure comprisesapplying a pressure from about 500 KPa to about 5000 KPa.
 16. A methodof singulating a wafer comprising: providing a wafer having a pluralityof die formed on the wafer and separated from each other by spaces,wherein the wafer has first and second opposing major surfaces, andwherein a layer of material is formed along the second major surface;placing the wafer onto a carrier substrate having an adhesive portion,wherein the layer of material is adjacent the carrier substrate;separating the wafer through the spaces to form singulation lines,wherein singulating lines terminate in proximity to the layer ofmaterial; and applying a pressure across the second surface of the waferto extrude the adhesive portion into the singulation lines to separatethe layer of material in the singulation lines, wherein portions of theseparated layer of material remain on the carrier substrate.
 17. Themethod of claim 1, wherein the applying step is repeated more than once.18. The method of claim 1, wherein applying the pressure comprisescompressing a static pressure balloon having a diameter greater thanthat of the wafer.
 19. The method of claim 1, wherein applying thepressure comprises using a fluid filled vessel, the method furthercomprising heating the wafer while applying the pressure.
 20. The methodof claim 19 further comprising placing a pressure plate between thefluid filled vessel and the carrier substrate before applying thepressure, wherein: providing the wafer comprises providing the layer ofmaterial having a thickness greater than about three microns; andapplying the pressure comprises a pressure between about 500 KPa toabout 5000 KPa.
 21. A method for separating a layer of material on awafer comprising: providing the wafer having a plurality of die formedon the wafer and separated from each other by singulation lines, whereinthe wafer has first and second opposing major surfaces, and wherein alayer of material is formed along the second major surface, and whereinthe singulation lines extend from the first major surface and terminateproximate to the layer of material, and wherein the wafer is attached toa carrier substrate; and simultaneously applying a pressure along theentire second major surface of the wafer through the carrier substrateto separate the layer of material in the singulation lines.